IM and Presence - How many servers/clusters do I need ?

[lgnmaia11267708]

Hi,

I've a question that is probably very straight forward and simple for the IMP gurus =). We are installing a fresh CUCM  v11.x, Unity 11.5, Expressway 8.9, Jabber 11.8 and IMP 11.5.

My question is specifically regarding the IMP servers.

Summary Design:

1. One CUCM Cluster in US with multiple subs in two different US DC's;

2. One CUCM Cluster in Europe with multiple subs in two different EU DC's;

3. Branch offices across the globe and around 15K extensions\users in total;

From the IM/Chat perspective, we have all users under the same internal domain. Since the latency is not a problem for IM services, why I would need a cluster in Europe for my deployment ? Can I just create one IMP cluster and attach to the US CUCM to cover all the 15K users ?

Thanks

Luiz

[Jaime Valencia]

Well, you can, assuming you meet the network requirements

Geographic Data Center Redundancy and Remote Failover

A Cisco IM and Presence Service cluster can be deployed between two sites with a single subcluster topology, where one server of the subcluster is in one geographic site and the other server of the subcluster is in another site. This deployment must have a minimum bandwidth of 5 Mbps, a maximum latency of 80 ms round-trip time (RTT), and TCP method event routing

But notice that ALL of the messages go through the IM&P server, meaning all that traffic, even if you're sending an IM to the guy in the office next to you, would have to go all the way to US and then back.

Also, depending on what features you use, like compliance for example, there might be some local regulations around where the data and the servers have to be physically at.

IMHO, you're better off just configuring inter-cluster peers for this.

[lgnmaia11267708]

Jaime, 

Thanks a lot for your answer. The Latency between the DCs is around 25ms, so all good. 

If I create another IMP cluster, is it the InterCluster lookup (ILS) going to take care to locate what is the Home IMP cluster for the user as it take care for the voice services ?

Just trying to understand if the same Home Cluster concept applies when it tries to find the user for the IMP

[Jaime Valencia]

Yes, ILS would make sure that you find your right server, then you find your IM&P server not via ILS, but via services profile associated to the user.

[Chris Deren]

The issue is an IMP cluster is part of single CUCM cluster, so if you have multiple CUCM clusters you should have separate IMP clusters (up to 3 sub clusters across 6 IMP nodes per cluster). There is no way to connect one IMP cluster to CUCM clusters. See SRND for more details:

A single Unified CM cluster supports only a single IM and Presence Service cluster; therefore, a separate IM and Presence Service cluster is required for each Unified CM cluster.

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab11/collab11/presence.html